Rheostat



, March 16 1926.

, 1,576,572 P. l. CHANDEYSSON Filed April 18, 19224v I. ckdndqyaon.

005513 l y r f'lH'otneq Y Patnted Mar. 16, 1926.

UNITED STATES vPATENT oFFlcE,

PIERRE I. CHANDIEYSSON, 0F ST. LOUIS, MISSOURI.

RHEOSTAT.

' Application tiled April 18, 1922. Serial N'o. 554,469.

To all '1v/wm t 'may concern:

Be it known that PIERRE I. CHANnm'ssoN, a citizen of the United Statesof America,

residing at pSt. Louis, in the county of St.-

LouisI and State of Missouri,'has invented certain new and usefulImprovements in Rheostats, of which the following is a speci- Iication.

V'lhis invention relates to improvements in rheostats and providesimeansof introducing or cutting out simultaneously, resist-ance into separateor distinct circu1ts.

Certain types of generators, notably low voltage machines, are providedwith two commutators for various reasons. These generators are operatedsometimes with the armature circuits in parallel, sometimes as threewire machines, and sometimes with the two commutators in series.

When so used, my rheostat permits of the excitation 0f such generator sothat each side or each commutator of the armature furnishes exactly onehalf of the exciting current, and it further gives the advantage thatwhen the generator is so connected, it can be operated either as a threevwire machine or as a two wire machine, with the outside leads eitherinparallel or in series without making any change whatsoever in the shuntconnections.

As constructed for commercial purposes preferably in accordance with thefollowing specification,

My rheostat, briefly will consist of two resistances', coiledgenerallyin one piece, each resistance embodying a plurality ofloops orturns at suitable intervals, which loops are fastened to a series ofposts insulated froml their support, the face of the post extendingabove the face of the support, constltuting a liat surface from which arubbing contact of suitable material can travel and conduct the currentfrom these surfaces to a suitably disposed conductor, on which the otherpart of the rubbing contact brush rests. Two such sets of resistancebinding posts with their projecting fiat contact surfaces are so mountedthat conducting brushes at the opposite extremity of a lever pivotedcentrally between them, can be moved thru an arc of about 180, andduring its travel, short-circuit simultaneouslyv on both sides thebinding posts to which the resistance is attached to the metallicsurface to which the current is admitted or from which the current isled away from the apparatus.

In the accompanying drawingswhich. illustrate a preferred embodiment of`my invention,

, Figure l is a plan View of the rheostat;

Figure 2 is a vertical sectional viewof the rheostat with the brushcarrying lever moved to a position about 90 spaced fromthat shown inFigure 1; and

Figure 3 is a diagrammatic view of the resistance, illustrating thecoils and ,theirl connections with the contacts'.

Referring more particularly to the drawings by numerals of reference, Iprovide a rheostat casing 2 of metal, said easing being of a dome-shapeto provide -therebeneath a recessed portion ,4 wlthin which are housedand protected, the coils of the rheostat to be later described, theflanges of which casing are provided with a suitable number of spacedears 6' by which the device may be attached to an instrument-board orwherever its service is required.

The crown o r upper face of the domeshaped casing is provided upon eachside of -a medium line with a semicircular series of wire to avolduncertain resistance of joints,

embodies a series of coils 16, each of which is formed of a suitablenumber of convolutions, said coils being provided with inter-connectingportions 18 of U-shape which straddle the extension of the contactshank, and

upon the threaded end 19 of which is applied a nut 20 which clamps orbinds the portions 18 securely against the under face of the nut 12 andin good electrical contact therewith.

The current is led into the rheostat thru a connector 22 having a socket24 into which is inserted the bared end of the conductor, which latteris bound by screws 25, said connector being secured upon the upper faceof the casing by a screw 26 also suitably insulated. Said connector isfurther secured in position thru a bolt 28 which passes thru the innerend thereof and thru the end one of the series of openings 8 in thecasing and pin 59. The lever is from which it is insulated by the sameplate of insulating material which serves for the several contacts.

The terminal of the last coil is bound to the shank of the contact whichis designated at 10, the interconnecting portions between the severalcoils being connected as has been stated to the shanks of the severalcontacts until finally the terminal of the rst coil is bound between thenuts 30 and 31 of the bolt 28 which secures the connector 22 on thecasing and also serves as the conductor.

Concentric with4v each series of contact 10 andai-ranged inwardlythereof is an arenate electrica-l contact rubbingV plate or strip 34 oneend of whicl1 terminates adjacent the last of the contacts and issecured upon the crown or upper face of the casing thru bolts 36 passingthru openings 38 arranged in said casing, said bolts and said Contactstrip being insulated by the insulating sheets 14. The strip 34 ispreferably formed integral with an outlet connector 40 similar to theinlet connector 22. i

The switch i member which brings into operation the Variable resistancein the circuit in which the rheostat is included comprises a lever 42having a pair of diametrically opposite arms 44 provided adjacent theirends and upon the lower face of each with a socket 46 Within which isdisposed a bridge piece 48 of suitable material, for instance, springcopper leaves, said bridge iece being suitably secured within the sockety such means as an insulated bolt and nut arrangement 50 and insulatedfrom the supporting arm by an insulation sheet 52.

The lever 42 is mounted for oscillation upon a post 54 journalledcentrally of the upper face of the-casing in an enlargement y arotatable element journaled 1n the casing,

thereof and is urged downwardly to maintain the bridge piece 48 incontact with the contact members 10 and 34 by a tension spring 56 coiledaround the lower extension ofthe post 54 and seated intermediate thelower facey of the enlargement and 'a cross provided with a knot 60 foroperating it. f

It is obvious that the current entering by the terminal connectors 22passes thru the coils, across the bridge members of the switch lever,back thru the rubbing contact strips and out at the terminals 40.

` It is evident from the description that my rheostat can be lutilizedfor other purposes than to regulate the current in two parts of thef/ieldfl circuit of a motor or a generator; for instance, the twoindependent reslstances I claim is 1. A rheostat comprising a4substantially dome shaped 'casing provided with a plu-- rality of sets`of spaced contacts, anl arcuate contact plate arranged adjacent each setof spaced contacts, a resistance element sup-'- ported in the dome ofsaid casing and connected with certain of the contacts, said` resistanceelement comprising a vseries of spiral coils with interconnecting loops,said loops adapted to straddle the aforesaid contacts, a rotatableelement journaled on the casing, and U-shaped conductors carried therebyand adapted to bridge the spacesbetween the plates and the spacedcontacts.

2. A. rheostat comprising a substantially dome shaped casing providedwith a, plurality of sets of spaced contacts, an arcuate contact platearranged adjacent each set of spaced contacts, a resistance elementsupported in the dome ofsaid casing and connected with certain of thecontacts, Said resistance element comprising a series of spiral coilswith interconnecting loops, said loops adapted to straddle the'aforesaid contacts,

and having arms extending laterally therefrom, said arms being providedwith concaved sockets on their lower sidesv and U- shaped conductorscarried in said sockets and adapted to bridge the spaces between theplates and the spaced contacts.

In testimony whereof I aflix my signature.

PIERRE I. CHANDEYSSON.l

